anatomy of rivers - quilcene school district #48 · flood plain •a flood plain is the area of...
TRANSCRIPT
Anatomy of Rivers
Watershed
• Any area of land where all precipitation collects and drains off into a common outlet, such as into a river or bay.
Columbia River Watershed
Major Watersheds of North America
Mississippi River Watershed
Continental Divide• The line that separates water that flows to the Pacific
Ocean and the Atlantic Ocean.
Only One Place Goes Both Directions-Two Ocean Pass
• Near Yellowstone National Park
V-shaped Valleys
• When rivers carve into mountains, they form steep V-shaped valleys.
Headwaters
• Source of a river (usually a spring or glacier/snow field)
Lake Itasca, MN, the headwaters of the Mississippi River
Main Stem (or Trunk)
• Main section of the river heading toward the ocean
Mississippi River on the Iowa/Wisconsin Border
Mississippi River at St. Louis, MO
Braided Streams
• When the plain is very flat, the river will begin to spread out looking for the quickest way through the sediment.
• Each little stream will begin to meander back and forth, sometimes spreading away from each other, sometimes rejoining later on.
• These braided streams often have thousands of little “islands”.
Flat Plains = Meandering River
Oxbow Lake
Oxbow Lakes
How a Meandering River can Form an Oxbow Lake
Flood Plain• A flood plain is the area of deposition
along a river. Often these areas flood over and over again, continually depositing more sediment.
• Often people build along flood plains because it is good farmland, only to see their cities destroyed by floods.
Tributary and Confluence
• Tributary: a stream or river that flows into a larger river
• Confluence: The meeting of two rivers
Mouth – where the river empties into the ocean or lake
River Deltas
• River deltas are where rivers enter the ocean or lakes. These deltas are the final place of deposition where silt and sand accumulate.
Mouth of the Columbia River
Estuary- zone where freshwater and saltwater mixes
Deltas at the Mouths of River Usually Provide Sand for Beaches
• Long Beach Peninsula formed due to sediment from the Columbia River being moved north from the mouth.